Production of epoxy compounds from olefinic compounds

ABSTRACT

Olefin is reacted with alkyl hypochlorite and water to produce an effluent containing the chlorohydrin and alkanol. An organic solvent is employed to extract the alkanol and chlorohydrin from the aqueous effluent, followed by saponification with base to produce olefin oxide. Olefin oxide is separated from the saponification effluent, followed by separation of an organic phase of the organic solvent, and an aqueous phase, which contains the alkanol. The aqueous phase containing alkanol, is chlorinated to produce the alkyl hypochlorite, with the organic phase being recycled to the extraction. The process is preferably integrated with the electrolytic production of chlorine.

This is a division of application Ser. No. 35,560, filed May 3, 1979,now U.S. Pat. No. 4,277,405, issued July 7, 1981.

This invention relates to the production of epoxy compounds, and moreparticularly to a new and improved process for producing epoxy compoundsfrom olefinically unsaturated compounds via the chlorohydrin.

U.S. Pat. No. 4,008,133 describes a process for producing epoxycompounds from olefins, via the chlorohydrin, and is particularlyrelated to a process for producing epoxy compounds which is integratedwith an electrolytic process for producing chlorine, whereby the epoxycompound can be produced from olefin and water, as net startingmaterials. The present invention is directed to an improvement in aprocess for producing epoxy compounds from olefins, via thechlorohydrin.

In accordance with the present invention, there is provided animprovement in a process for producing an epoxy compound wherein atertiary alkanol is chlorinated to produce tertiary alkyl hypochlorite,the tertiary alkyl hypochlorite is contacted with an olefinicallyunsaturated compound and water to produce a reaction effluent containingtertiary alkanol and chlorohydrin, and the chlorohydrin is saponified toproduce the epoxy compound. In accordance with the improvement of thepresent invention, organics present in the chlorohydrin reactioneffluent are recovered by use of an organic extraction solvent wherebythe organic extraction solvent includes the chlorohydrin and tertiaryalkanol. The organic extraction solvent, containing the chlorohydrin andtertiary alkanol is contacted with an aqueous base to effectsaponification of the chlorohydrin to the corresponding epoxy compound.The epoxy compound is separated from the saponification effluent.Tertiary alkanol present in the saponification effluent is extractedinto an aqueous phase which is employed in the hypochlorite production,and organic solvent is recycled to the chlorohydrin effluent extraction.

More particularly, tertiary alkanol is contacted with chlorine in thepresence of aqueous caustic such as calcium hydroxide, potassiumhydroxide, sodium hydroxide, etc., preferably sodium hydroxide, toconvert the tertiary alkanol to tertiary alkyl hypochlorite. Thetertiary alkyl hypochlorite is then reacted with olefinicallyunsaturated compound and water to produce the corresponding chlorohydrinand tertiary alkanol. Chlorohydrin and tertiary alkanol are extractedfrom the effluent by use of an organic solvent which may be present inthe chlorohydrin production or added to the effluent. The organicextract is then contacted with a suitable aqueous base, such as sodiumhydroxide, potassium hydroxide, calcium hydroxide, etc., preferablysodium hydroxide, to effect saponification of the chlorohydrin to thecorresponding epoxy compound. The epoxy compound is recovered asproduct. Tertiary alkanol present in the saponification effluent isextracted into an aqueous phase for recycle to hypochlorite production.Organic solvent is recycled to the chlorohydrin effluent extraction.

The organic solvent employed in the process is inert, immiscible withthe aqueous phases present in the process, and is a solvent for alkanoland chlorohydrin employed and/or produced in the process. The term"inert" as used herein means that the extraction solvent does notadversely affect the various reactions. As representative examples ofsuitable solvents, there may be mentioned: chlorinated hydrocarbons,including chlorinated aromatics and chlorinated aliphatics (saturated);e.g., chlorobenzene, chlorinated paraffins, such as carbontetrachloride, chloroform, dichloropropane, polychlorinated paraffins,etc.; chlorinated ethers; e.g., bis (chloroisopropyl) ether, ketones andthe like. Such solvents may be employed alone or as a mixture of two ormore thereof. In accordance with a preferred aspect, the organic solventhas a boiling point less than the aqueous caustic solution employed forthe saponification to facilitate recovery of the epoxy compound by steamstripping; i.e., reduction of reboiler temperature and lower steamconsumption.

The aqueous alkali employed for the hypochlorite production andsaponification may be the same or different alkali. Similarly, thealkali can be obtained from any one of a wide variety of sources. Inaccordance with a preferred procedure, the epoxy production isintegrated with an electrolytic process for producing chlorine; however,the scope of the invention is not limited to such a preferred procedure.For example, chlorine can be obtained from other sources and/or alkalican be provided other than from the electrolytic cell.

In accordance with the preferred aspect of the present invention,gaseous chlorine is produced in an electrolytic cell by the electrolysisof an aqueous brine solution, with chlorine being produced at the anodeand sodium hydroxide and hydrogen at the cathode. The gaseous chlorineproduced in the electrolysis cell is reacted with a tertiary alkanol inan aqueous solution, containing sodium hydroxide and sodium chloride,obtained from the cathode compartment of the electrolytic cell toproduce a tertiary alkyl hypochlorite. An organic phase, containing thetertiary alkyl hypochlorite, is recovered from the first reaction zoneand contacted in a second reaction zone with an olefinically unsaturatedcompound and water to produce the corresponding chlorohydrin. An organicextraction solvent is employed to extract organics from the aqueouseffluent, containing chlorohydrin and tertiary alkanol. The organicextract, including chlorohydrin and tertiary alkanol, is contacted withan aqueous solution of sodium hydroxide and sodium chloride, obtainedfrom the cathode compartment of the electrolytic cell, to produce fromthe chlorohydrin the corresponding epoxy compound, which is recovered asreaction product. Epoxy compound is recovered as reaction product.Tertiary alkanol present in the effluent is extracted into an aqueousphase, which may be the aqueous phase present in the saponificationeffluent or an aqueous phase provided from the hypochlorite production,with the tertiary alkanol in the aqueous phase being recycled to thehypochlorite production. Organic solvent is recycled to the chlorohydrineffluent extraction.

In accordance with a preferred aspect, the electrolyte fed to the anodehas a sodium chloride concentration from about 170 to about 400 gramsper liter of water, and preferably from about 200 to about 350 grams perliter of water. In the electrolytic cell, chlorine is produced at theanode and hydrogen and sodium hydroxide are produced at the cathode.

Chlorine produced in the electrolytic cell is introduced into ahypochlorite production reaction zone wherein the chlorine is reactedwith a tertiary alkanol, preferably a tertiary alkanol having from 4 to6 carbon atoms, and most preferably tertiary butanol or tertiaryamylalcohol, and sodium hydroxide in an aqueous brine solution, obtainedfrom the electrolytic cell.

In general, the hypochlorite production reactor is operated at atemperature from about 5° to 220° F., preferably at a temperature fromabout 32° to 160° F., a pressure from about 5 psia to 100 psia,preferably from about 10 psia to 50 psia.

In order to minimize the amount of free chlorine present in the alkylhypochlorite organic phase introduced as feed to the chlorohydrinreactor, the hypochlorite production reaction can be effected without asubstantial molar excess of chlorine with respect to sodium hydroxide.Accordingly, in order to minimize the quantity of free chlorine presentin the hypochlorite reaction product, the molar ratio of chlorine tosodium hydroxide generally does not exceed about 1.05 to 1, and ispreferably at about stoichiometric proportions; i.e., about 1:1.

In accordance with a preferred operation, the hypochlorite productionreaction is effected in a manner such that the alkyl hypochlorite isformed as a separate organic phase to thereby eliminate the necessity ofextracting the hypochlorite from the aqueous phase. In order to providea separate organic phase, the hypochlorite production reaction iseffected at a chlorine to sodium hydroxide mole ratio of at least 0.5:1.Thus, in accordance with the preferred operation, the hypochloriteproduction reaction is effected with chlorine to sodium hydroxide moleratios of from about 0.5:1 to 1.05:1, and preferably from about 0.9:1 to1:1.

In regard to the amount of tertiary alkanol employed with respect to theamount of sodium hydroxide, it is preferred to operate the hypochloriteproduction reactor without a substantial molar excess of sodiumhydroxide with respect to the tertiary alkanol. In general, the moleratio of tertiary alkanol to sodium hydroxide is from about 0.75:1 toabout 1.1:1.

It is to be understood that the cell liquor could be partiallychlorinated in a separate vessel by contact with a portion of theoverall chlorine requirements to produce sodium hypochlorite, with theremainder of the chlorine requirements, the t-alkanol and partiallychlorinated cell liquor being introduced into the hypochloriteproduction reaction. In such a two-step process, in general, less thanabout one-half of the total chlorine requirements are employed in thefirst stage to produce the sodium hypochlorite.

An aqueous brine phase and an organic phase, containing thehypochlorite, are separately recovered from the hypochlorite productionreactor. The aqueous brine phase may then be introduced into theelectrolytic cell, as electrolysis feed whereby the chlorine values arerecovered therefrom.

The organic phase, recovered from the hypochlorite production reactor isthen introduced into the chlorohydrin production reactor. In thechlorohydrin production reactor, the tertiary alkyl hypochlorite,preferably tertiary butyl hypochlorite is contacted with an olefinicallyunsaturated compound and water, which is essentially free of chlorideion, to produce the chlorohydrin.

The production of chlorohydrin is preferably effected as hereinaboveindicated, with water which is essentially free of chloride ion in thatit has been found that the presence of chloride ion, in the aqueousphase, reduces the production of the desired chlorohydrin product. Thewater employed as feed to the chlorohydrinator should not contain achloride ion concentration in excess of 1 mole/liter, and preferably thechloride ion concentration should not exceed 0.3 mole/liter. The term"essentially free of chloride ions" encompasses a chloride ionconcentration of from 0 to 1 mole of chloride ions per liter of water.Furthermore, the presence of chlorine in the chlorohydrin productionreactor should be avoided in that such chlorine is converted to thedichloro derivative, rather than the desired chlorohydrin; however, as aresult of equilibrium considerations, some dissolved chlorine isintroduced with the tertiary alkyl hypochlorite. The amount of freechlorine is maintained as low as possible, and generally does not exceed7 moles of chlorine per 100 moles of hypochlorite. It is to beunderstood that greater amounts of chlorine could be present, but suchgreater amounts reduce the yield of chlorohydrin.

In accordance with a preferred procedure, it has been found that thepresence of some salt in the aqueous portion of the chlorohydrineffluent favors extraction of the chlorohydrin and t-alkanol productinto the organic phase, thereby facilitating subsequent separation ofthe effluent into an aqueous phase, for recycle to the chlorohydrinproduction, and an organic phase, which includes the t-alkanol andchlorohydrin as feed to the saponification. Such salts may include oneor more of sodium chloride, sodium sulfate, sodium carbonate, potassiumcarbonate, calcium chloride, potassium fluoride, etc. Sodium sulfate maybe preferred. The salt is employed in concentration which enhancesextraction of organics into the organic phase without adverselyaffecting chlorohydrin production. Thus, if the salt is a chloride, thechloride ion concentration should be below 1 mole per liter of water.

Thus, in a accordance with the present invention, the chlorohydrineffluent is separated into an aqueous phase, which is recycled to thechlorohydrin production reactor, in a manner consistent with theprocedure of U.S. Pat. No. 4,008,133, and an organic phase, containingthe organic solvent, chlorohydrin and t-alkanol (with only a minimalamount of dissolved water) which may be employed as feed to thesaponification. Such organics are therefore recovered without requiringdistillation.

The chlorohydrination of the olefin, with the tertiary alkylhypochlorite, in water, is preferably effected at a temperature fromabout 70° to about 140° F., and a pressure from 1 psig to about 300psig. It is to be understood, however, that such conditions are notlimiting, and the selection of particular conditions is deemed to bewithin the scope of those skilled in the art from the teachings herein.The chlorohydrination is preferably effected by concurrent contact in amultistaged stirred reactor, but it is to be understood that cocurrentor countercurrent operation or in a single stage reactor could beemployed.

Organics are extracted from the effluent by the use of an organicextraction solvent, which can be added to the effluent, or in thealternative could be introduced into the chlorohydrin productionreactor. In general, such extraction is effected at an elevatedtemperature in that higher temperatures tend to favor the equilibriumconcentration of the tertiary alkanol in the organic extraction solvent.This is particularly true where the aqueous concentration in theeffluent is low; i.e., ten weight percent or lower. Thus, for example,such extraction may be effected at temperatures in the order of fromabout 150° to 200° F. in order to favor the equilibrium concentration ofthe tertiary alkanol into the organic solvent phase. As previouslyindicated, the presence of salt in the aqueous phase also favorsextraction of organics.

The organic extract is then saponified by direct contact with cellliquor obtained from the cathode compartment of the electrolytic cell,which contains sodium hydroxide and sodium chloride, which reacts withthe chlorohydrin to produce the epoxy compound. In general, thesaponification is effected at temperatures in the order of from about150° to about 250° F., preferably from about 180° to about 230° F., atthe pressure of the system.

The epoxy compound is recovered from the saponification effluent. Inaccordance with the present invention, tertiary alkanol present in thesaponification effluent is recovered for recycle to the hypochloriteproduction by extracting the tertiary alkanol into an aqueous phase; inparticular either aqueous brine from the saponification and/or anaqueous phase derived from the electrolytic cell and/or aqueous brinefrom the hypochlorite production.

In accordance with one embodiment, the tertiary alkanol ispreferentially extracted into the aqueous brine phase of thesaponification effluent. Such preferential extraction may beaccomplished by the use of reduced temperatures in that lowertemperatures favor the equilibrium concentration of tertiary alkanolinto the aqueous brine. Thus, for example, temperatures in the order of90° F. to 115° F. may be employed.

As hereinabove noted, the presence of salt in the aqueous phase reducesthe solubility of tertiary alkanol in the aqueous phase. As a result, inorder to increase the tertiary alkanol carrying capacity of the aqueousphase present in the saponification effluent, the volume of such phasemay be increased by employing all or portion of the cell liquor to beemployed as feed to the hypochlorite production in the organic-aqueousphase separation of the saponification effluent. Thus, the tertiaryalkanol is recovered fron the saponification effluent in a combinedaqueous phase of aqueous brine present in the saponification effluentand cell liquor to be used as feed to the hypochlorite production, withthe combined aqueous phase, including tertiary alkanol being introducedinto the hypochlorite production step. As hereinabove described, suchextraction is favored by lower temperatures.

The volume of such aqueous phase may also be increased by use of aportion of the brine recovered from the hypochlorite production,resulting in the tertiary alkanol being recovered and recycled to thehypochlorite production in a combined aqueous phase comprised of brineproduced in the saponification and hypochlorite production. In such anembodiment, there is an internal brine "loop" between the saponificationeffluent phase separation and the hypochlorite production. Ashereinabove described such extraction is favored by lower temperatures.

As a further embodiment, the saponification effluent may be separatedinto an organic phase and an aqueous brine phase at an elevatedtemperature whereby the tertiary alkanol is extracted into the organicsolvent phase. The aqueous brine phase is ultimately recycled to theelectrolytic cell.

The tertiary alkanolis then extracted from the organic solvent into anaqueous phase which is aqueous brine recovered from the hypochloriteproduction, with the tertiary alkanol being recycled to the hypochloriteproduction in such aqueous phase. In this manner, there is establishedan internal brine "loop" between such extraction and the hypochloriteproduction. Such extraction is effected at the hereinabove noted lowertemperatures. In addition, the brine concentration is lower than thebrine of the saponification effluent.

The organic solvent present in the saponification effluent is recoveredand recycled to the chlorohydride effluent extraction. As should beapparent, it is not necessary that the organic solvent be free oftertiary alkanol in that such organic solvent is passed in an internalloop between the chlorohydrin effluent extraction and thesaponification.

Thus, in accordance with such integrated process the brine produced inthe hypochlorite production and saponification steps is ultimatelyrecycled to the cell, and the tertiary alkanol produced in thechlorohydrin production step is recovered in an aqueous phase andrecycled to the hypochlorite production.

In accordance with a modified embodiment, the organic phase recoveredfrom the saponification effluent could be contacted with brine freewater to "wash" tertiary alkanol therefrom prior to the subsequentextraction step. The tertiary alkanol in such a water extract could thenbe introduced into the hypochlorite production reactor.

As yet another variation, a portion of the aqueous chlorohydrinproduction effluent by-passes the extraction step and is fed directly tothe saponification reaction. Alternatively, the by-pass portion could befed directly to a secondary saponification reactor, followed byseparation of a crude olefin oxide stream and an aqueous streamcontaining tertiary alkanol in aqueous brine for introduction into thehypochlorite production reactor.

In accordance with another embodiment, the aqueous raffinate recoveredfrom the extraction step, which is to be recycled to the chlorohydrinproduction reactor may be treated to separate any residual organicextraction solvent; e.g., the organic extraction solvent may be removedin a stripping operation utilizing live steam or olefin as strippingagent. Such aqueous raffinate may also contain tertiary alkanol, whichwould be stripped overhead along with the organic solvent. In somecases, final separation of such tertiary alkanol from the organicsolvent may be warranted, and this could be accomplished by extractingthe tertiary alkanol from the recovered organic extraction solvent witha brine slip stream which is to be introduced into the hypochloriteproduction reactor.

The olefinically unsaturated compound employed as feed in the presentprocess may be any one of a wide variety of olefinically unsaturatedcompounds, including both mono-olefinically and diolefinicallyunsaturated compounds. The olefinically unsaturated compounds generallyemployed as feed are represented by the following structural formula:

    R.sub.1 --CH═CH--R.sub.2

wherein R₁ and R₂ are each separately either hydrogen; alkyl; halo,naphthyl or phenyl substituted alkyl; halo or alkyl substituted phenyl;phenyl; naphthyl; halo or alkyl substituted naphthyl; alkenyl or halosubstituted alkenyl; and R₁ and R₂ can be linked together to provide acycloalkene (generally 5 to 10 carbon atoms). The alkyl and alkenylgroups generally contain 1 to 6 carbon atoms and the halo group ispreferably iodo-, bromo-, or chloro-, most preferably chloro-. Asrepresentative examples of the most suitable feedstocks, there may bementioned; alkenes having from 2 to 6 carbon atoms, preferably 2 to 4carbon atoms with ethylene and propylene being particularly preferred;styrene; cyclohexene; stilbene; butadiene; chloroprene; allyl chloride,allyl bromide; bromoprene; cyclohexene; and cyclpentene. The epoxycompounds generally produced in accordance with the invention arerepresented by the following structural formula: ##STR1## wherein R₁ andR₂ are as defined above.

The invention will be further described with respect to a preferredembodiment thereof, illustrated in the accompanying drawing wherein:

FIG. 1 is a simplified schematic flow diagram of an embodiment of theprocess of the present invention; and

FIG. 2 is a simplified flow diagram of another embodiment.

The preferred embodiment will be particularly described with respect tothe production of propylene oxide (1, 2-epoxy propane), but it is to beunderstood that the embodiment is also applicable to the production ofother epoxy compounds; e.g., epichlorohydrin from allyl chloride.

Referring to the drawing, there is shown an electrolytic cell,schematically generally indicated as 10, wherein, as known in the art,hydrogen is produced at the cathode, and chlorine at the anode, usingsodium chloride as electrolyte. The hydrogen is withdrawn from the cell,as net product, through line 11. Chlorine produced in the cell iswithdrawn therefrom through line 12, and caustic cell liquor, containingsodium hydroxide and sodium chloride, dissolved in water, is withdrawnfrom the cell through line 13.

The chlorine in line 12 is introduced into a hypochlorite productionreactor, schematically indicated as 14 wherein the chlorine contacts atertiary alkanol; in particular, tertiary butanol and caustic cellliquor to effect production of tertiary alkyl hypochlorite. The causticcell liquor, containing sodium chloride and sodium hydroxide, may beprovided directly from the cell through line 15 or may be provided in arecycle brine stream, containing tertiary butanol, as hereinafterdescribed. The tertiary butanol is provided through line 16 in a recycleaqueous brine stream, which may or may not be supplemented with causticcell liquor, as hereinafter described.

The hypochlorite production reactor 14 is operated as hereinabovedescribed to effect chlorination of the tertiary butanol to tertiarybutyl-hypochlorite, which is recovered as an organic stream through line17.

The production of the hypochlorite and the recovery of the hypochloritemay be effected as described in U.S. Pat. No. 4,008,133, which is herebyincorporated by reference.

The hypochlorite in line 17 is introduced into a chlorohydrin productionreaction zone, schematically generally indicated as 18. Propylene, inline 19, as well as a recycle aqueous stream in line 21 are alsointroduced into the chlorohydrin production reaction zone 18. Thechlorohydrin production reaction zone 18 is operated at conditions ashereinabove described to effect conversion of the propylene to propylenechlorohydrin. The chlorohydrin production reactor 18, generally includesmeans for mixing of the three phases present in the reactor; namely, agaseous phase, as well as organic and aqueous phase, and suchchlorohydrin production may be effected as described in U.S. Pat. No.4,008,133. It is to be understood that in some cases a catalyst may beintroduced into the chlorohydrin production zone in order to increasechlorohydrin production rate.

A liquid reaction effluent, which contains water, tertiary butanol,propylene chlorohydrin, as well as any reaction by-products, iswithdrawn from the propylene chlorohydrin production reactor 18 throughline 22 and introduced into an extraction column, schematicallyindicated as 23, wherein the effluent is contacted with an organicextraction solvent introduced through line 24. In particular, theorganic extraction solvent could be, for example, dichloropropane,carbon tetrachloride or mixtures thereof. As a result of such contact,organics present in the chlorohydrin production reaction effluent areextracted into the organic solvent phase (propylene chlorohydrin,tertiary butanol, as well as reaction by-products) which is withdrawnfrom the extraction column 23 through line 25.

An aqueous raffinate is withdrawn from extraction column 23 through line25, and as hereinabove noted, such aqueous raffinate may include someorganic solvent, as well as residual tertiary butanol. If required, ashereinabove described, such organics may be removed in a separateoperation, from such aqueous raffinate. The aqueous raffinate in line26, with or without treatment to remove organics, is combined withmakeup water in line 27, and introduced through line 21 into thepropylene chlorohydrin production reactor 18.

The organic extract in line 25 is introduced into a saponificationreaction zone, which is preferably in the form of a combinationsaponifier-stripping tower, which is schematically generally indicatedas 31. In the saponification reaction zone 31, the organic extract iscontacted with caustic cell liquor containing sodium hydroxide, sodiumchloride and water, obtained from the electrolysis cell 10, andintroduced into the saponification reactor 31 through line 32. As aresult of such contact, the propylene chlorohydrin is converted topropylene oxide, and the hydrogen chloride released is neutralized bythe sodium hydroxide present in the cell liquor to produce sodiumchloride and water.

Crude propylene oxide, which may contain light end products, such as,acetone, is withdrawn from the saponification reactor-stripping tower 31through line 33 for introduction into a propylene oxide purificationsection, schematically generally indicated as 34, wherein light endimpurities are separated from the propylene oxide. Propylene oxide isrecovered as product through line 35, with the light end impuritiesbeing recovered through line 36.

Referring back to saponifier-stripping tower 31, a bottoms, containingwater, sodium chloride, tertiary butanol, organic solvent, as well asheavier by-products, is withdrawn from the stripping portion of thesaponifier through line 37 and introduced into a separator,schematically generally indicated as 38 in order to effect separation oforganic and aqueous phases. In accordance with one embodiment, separator38 is further provided with caustic cell liquor from the electrolysiscell 10 through line 39 in order to increase the ability of the aqueousbrine phase to carry tertiary butanol. In accordance with anotherembodiment, separator 38 may be provided through line 45 with brinerecovered from the hypochlorite production to increase the alkanolcarrying capacity of the aqueous phase by increasing the bulk volumethereof. It is to be understood, however, that in some cases theseparation can be conducted without the addition of additional aqueousmaterial. The separation in separator 38 is effected in a manner suchthat the equilibrium concentration of tertiary butanol is in favor ofthe aqueous brine phase.

An aqueous brine phase, which contains tertiary butanol, and which mayfurther contain sodium hydroxide, if cell liquor is provided throughline 39, is withdrawn from separator 38 through line 16 for introductioninto the hypochlorite production reactor 14. Make up tertiary butanol,if required, may be provided through line 41. All or a portion of thecaustic requirements, or none of the caustic requirements for thehypochlorite production reactor 14 may be provided through line 16,depending on whether or not cell liquor is provided to separator 38through line 39. The remaining portion of the caustic requirements, ifany, are provided by the introduction of cell liquor through line 15.

An aqueous brine phase is withdrawn from the hypochlorite productionreactor 14 through line 42 for recycle to the electrolytic cell 10. Aportion of the brine solution may be passed through line 45 to separator38, as hereinabove described. All or a portion of the remaining brinesolution may be directly recycled to electrolytic cell 10; however, inaccordance with a preferred embodiment, at least a portion of suchrecycle brine solution is introduced into a brine purification section,schematically generally indicated as 43 in order to remove organiccontaminants therefrom. Such purification may be effected as describedin U.S. application Ser. No. 851,853, filed on Nov. 16, 1977, which ishereby incorporated by reference. The recycled brine solution isintroduced into the electrolytic cell 10 through line 44.

Referring back to separator 38, an organic phase, containing theextraction solvent, as well as some tertiary butanol and heavierby-products, is withdrawn from separator 38 through line 47 for recycleto the extraction column 23 through line 24. A slip-stream of suchorganic phase may be withdrawn through line 48 for introduction withlight impurities in line 36 into an incinerator, along with molecularoxygen, as described in U.S. Pat. No. 4,008,133.

Alternatively, all or a portion of such organic by-products may beseparately recovered. As a further alternative, the extraction solventmay be water "washed" in order to remove tertiary butanol therefrom,which such tertiary butanol being ultimately introduced into thehypochlorite production reactor 14.

A further embodiment of the invention is shown in FIG. 2 of thedrawings. The embodiment of FIG. 2 is similar to the embodiment of FIG.1, except for the recovery of tertiary alkanol from the saponificationeffluent for recycle to the hypochlorite production. As a result, theembodiment of FIG. 2 will be particularly described only with respect tosuch recovery portion. In FIG. 2, prime numerals are employed todesignate the portions of the embodiment similar to the embodiment ofFIG. 1.

Referring to FIG. 2, a bottoms containing water, sodium chloride,tertiary butanol, organic solvent, as well as heavier by-products, iswithdrawn from the stripping portion of the saponifier through line 37'and introduced into a separator 101 to separate organic and aqueousphases. The separation in separator 101 is conducted at conditions suchthat essentially all of the tertiary butanol is extracted into theorganic phase; i.e., higher temperatures and higher salt concentrations.

Aqueous brine is withdrawn from separator 101 through line 102 and maybe combined with net brine from the hypochlorite production for recycleto the electrolysis.

An organic phase containing the tertiary butanol withdrawn fromseparator 101 through line 103 is combined with the brine in line 45'recovered from the hypochlorite production and the combined streamintroduced into a second separator 105. The separator 105 is operated atconditions which favor extraction of the tertiary butanol into theaqueous phase, i.e. lower temperatures and lower salt concentrations.

Aqueous brine, containing tertiary butanol is withdrawn from separator105 through line 106 and recycled to the hypochlorite production.

Organic solvent is recovered from separator 105 through line 47' forrecycle to the chlorohydrin effluent extraction.

In accordance with this embodiment, it is possible to effect t-butanolrecovery while maintaining a higher salt concentration in the brinerecycle from the saponification. Such higher salt concentration isadvantageous in the operation of the electrolytic cell. Thus, forexample, whereas the saponification effluent brine should have arelatively low salt concentration (17-18 wt%) to provide for economicextraction directly into the aqueous phase, by proceeding in accordancewith the embodiment of FIG. 2 it is possible to employ higher saltconcentrations, e.g., about 25 wt%, whereby the concentration of totalbrine recycled to the cell is increased.

Although the invention has been described with respect to preferredembodiments, it is to be understood that such embodiments may be variedin numerous ways within the spirit and scope of the present invention.As a result, the present invention is not limited to such embodiments.

For example, as hereinabove noted, the invention is also applicable tothe production of epoxy compounds by use of hypochlorite withoutintegration with electrolytic production of chlorine. Thus, the chlorineand/or the aqueous base employed in the hypochlorite production and/orsaponification may be obtained from other sources. Thus, the presentinvention is generally applicable to the production of epoxy compoundsby use of hypochlorite wherein organics are recovered from thechlorohydrin production effluent in an organic solvent which is employedas feed to the saponification, with tertiary alkanol being ultimatelyrecovered from the saponification effluent in an aqueous phase which isrecycled to the hypochlorite production.

The present invention is further illustrated by the following example;however, the scope of the invention is not to be limited thereby:

EXAMPLE

The following presents in tabular form the temperatures, compositionsand flow rates of various streams of the embodiment illustrated in thedrawing (FIG. 1) with respect to the use of an organic extractionsolvent for effecting recovery of chlorohydrin and tertiary alkanol.

    ______________________________________                                        BASIS: 100 MM Lb/Yr. Propylene Oxide Production Capacity                                      Principal Component                                                                             Total                                       Stream                                                                              Temp.     Concentration Ranges                                                                            Flow Range                                  No.   Range (°F.)                                                                      (Weight %)        (M Lb/Hr.)                                  ______________________________________                                        24    150-200   5-15% t-BuOH (t-Butanol)                                                                         50-200                                                     Bal. DCP (Dichloropropane),                                                   etc.                                                          22    115-140   5-15% t-BuOH      100-400                                                     5-19% C.sub.3 H.sub.7 OCl                                                     Bal. H.sub.2 O                                                25    125-175   10-25% t-BuOH     100-250                                                     10-25% C.sub.3 H.sub.7 OCl                                                    Bal. DCP/etc.                                                 32    175-200   7-12% NaOH         75-150                                                     7-15% NaCl                                                                    Bal. H.sub.2 O                                                26    150-175   1-7% t-BuOH        75-200                                                     0-5% C.sub.3 H.sub.7 OCl                                                      Bal. H.sub.2 O                                                33    150-200   50-99% P.O.       12-25                                                       Bal. H.sub.2 O                                                37    175-250                     150-400                                     39     90-125   7-12% NaOH         0-150                                                      7-15% NaCl                                                                    Bal. H.sub.2 O                                                16     90-125   0-6% NaOH         200-900                                                     2- 7% t-BuOH                                                                  15-25% NaCl                                                                   Bal. H.sub.2 O                                                45     90-125   15-25% NaCl       100-800                                                     Bal. H.sub.2 O                                                ______________________________________                                    

The present invention is particularly advantageous in that it permitseffective production of an olefin oxide, while facilitating recovery ofvarious components produced in the process. In particular, the presentinvention provides for recovery of chlorohydrin and recycle alkanolwithout the necessity of employing costly azeotropic distillationprocedures.

The above advantages and others should be apparent to those skilled inthe art from the teachings herein.

Numerous modifications and variations of the present invention arepossible in light of the above teachings and, therefore, within thescope of the appended claims, the invention may be practised otherwisethan as particularly described.

What is claimed:
 1. In a process for producing an epoxy compound whereina tertiary alkanol is chlorinated in the presence of an aqueous base toproduce tertiary alkyl hypochlorite, the tertiary alkyl hypochlorite iscontacted with an olefinically unsaturated compound and water to producea reaction effluent containing water, tertiary alkanol and chlorohydrin,and the chlorohydrin is saponified with aqueous base to produce thecorresponding epoxy compound, the improvement comprising:extractingorganics from the chlorohydrin production with an organic extractionsolvent, said organics including the chlorohydrin and tertiary alkanol;contacting organic extract containing chlorohydrin and tertiary alkanol,and an aqueous base to effect saponification of the chlorohydrin to thecorresponding epoxy compound; recovering the epoxy compound produced inthe saponification; separating from the saponification an organicsolvent phase and an aqueous phase, said separation being effected withpreferential extraction of the tertiary alkanol into the aqueous phase;recycling organic solvent to said extracting of organic; and passingaqueous phase containing tertiary alkanol to the chlorination.
 2. Theprocess of claim 1 wherein an aqueous phase derived from thechlorination is employed in the separating to increase the tertiaryalkanol capacity of the separated aqueous phase.
 3. The process of claim1 wherein at least a portion of the aqueous alkali to be employed in thechlorination is employed in the separating to increase the tertiaryalkanol capacity of the separated aqueous phase.
 4. The process of claim1 wherein the separating is effected at a temperature of from 90° F. to115° F.
 5. The process of claim 1 wherein the organic extraction solventis comprised of at least one chlorinated hydrocarbon.
 6. The process ofclaim 1 wherein organic extract and unextracted chlorohydrin effluentare employed as feed to the saponification.
 7. The process of claim 6wherein the water employed in the chlorohydrin production has a saltdissolved therein to enhance extraction of the tertiary alkanol andchlorohydrin into the organic solvent, said water having a chlorideconcentration of less than 1 mole per liter of water.
 8. The process ofclaim 7 wherein a water phase is recovered from the chlorohydrinproduction and recycled to the chlorohydrin production.
 9. The processof claim 1 wherein the olefinically unsaturated compound is a compoundselected from the group consisting of compounds with the followingstructural formula:

    R.sub.1 --CH═CH--R.sub.2

wherein R₁ and R₂ are each separately selected from the group consistingof hydrogen; alkyl; halo-, naphthyl and phenyl substituted alkyl;phenyl; halo- and alkyl substituted phenyl; naphthyl; halo- and alkylsubstituted naphthyl; alkenyl and halo- substituted alkenyl; and R₁ andR₂ can be linked together to provide a cycloalkene having from 5-10carbon atoms.
 10. The process of claim 8 wherein the olefinicallyunsaturated compound is propylene.
 11. The process of claim 8 whereinthe olefinically unsaturated compound is allyl chloride.
 12. The processof claim 8 wherein the tertiary alkanol is tertiary butanol.
 13. Theprocess of claim 1 wherein the entire effluent from the chlorohydrinproduction is subjected to said extracting.
 14. In a process forproducing an epoxy compound which is integrated with the electrolyticproduction of chlorine wherein a tertiary alkanol is contacted withchlorine and aqueous electrolyte from the electrolytic cell, containingsodium hydroxide and sodium chloride to produce tertiary alkylhypochlorite and aqueous brine for ultimate recycle to the cell,tertiary alkyl hypochlorite is contacted with olefinically unsaturatedcompound and water to produce the corresponding chlorohydrin andtertiary alkanol, and chlorohydrin is contacted with aqueous electrolytefrom the electrolytic cell containing sodium chloride and sodiumhydroxide to produce the corresponding epoxy compound and aqueous brinefor ultimate recycle to the cell, the improvement comprising:extractingorganics from the chlorohydrin production with an organic extractionsolvent to produce an organic extract containing chlorohydrin andtertiary alkanol; contacting organic extract with the aqueouselectrolyte containing sodium chloride and sodium hydroxide to saponifychlorohydrin to the corresponding epoxy compound; recovering epoxycompound; separating from the saponification an organic solvent phaseand an aqueous brine phase, said separating being effected withpreferential extraction of the tertiary alkanol into the aqueous brinephase; recycling organic solvent to said extracting of organic; passingaqueous brine phase containing tertiary alkanol to said hypochloriteproduction.
 15. The process of claim 14 wherein an aqueous brine phasederived from the hypochlorite production is employed in the separatingto increase the tertiary alkanol carrying capacity of the separatedaqueous brine phase.
 16. The process of claim 14 wherein at least aportion of the aqueous electrolyte to be employed in the hypochloriteproduction is initially employed in the separating to increase thetertiary alkanol carrying capacity of the separated aqueous brine phase.17. The process of claim 14 wherein the separating is effected at atemperature of from 90° F. to 115° F.
 18. The process of claim 14wherein a water phase is recovered from the chlorohydrin production andrecycled to the chlorohydrin production.
 19. The process of claim 18wherein the water employed in the chlorohydrin production has a saltdissolved therein to enhance extraction of the tertiary alkanol andchlorohydrin into the inert organic solvent, said water having achloride concentration of less than 1 mole per liter of water.
 20. Theprocess of claim 18 wherein the olefinically unsaturated compound is acompound selected from the group consisting of compounds with thefollowing structural formula:

    R.sub.1 --CH═CH--R.sub.2

wherein R₁ and R₂ are each separately selected from the group consistingof hydrogen; alkyl; halo-, naphthyl and phenyl substituted alkyl;phenyl; halo- and alkyl substituted phenyl; naphthyl; halo- and alkylsubstituted naphthyl; alkenyl and halo- substituted alkenyl; and R₁ andR₂ can be linked together to provide a cycloalkene having from 5-10carbon atoms.
 21. The process of claim 20 wherein the tertiary alkanolis tertiary butanol.
 22. The process of claim 21 wherein theolefinically unsaturated compound is propylene.
 23. The process of claim21 wherein the olefinically unsaturated compound is allyl chloride. 24.The process of claim 14 wherein the organic extraction solvent iscontacted with brine free water to recover remaining tertiary alkanoland the water extract is passed to the hypochlorite production.
 25. Theprocess of claim 14 wherein only a portion of a chlorohydrin productioneffluent is subjected to said extracting.